misterbleepy, thanks for the post. Truly a massive energy-storage and power-generating system. It took them over ten years to build and become operational, probably at an astronomical price. 75% efficient, but interesting that they can get a generator on-line in only ten seconds.

Only three such sites in the UK.

Musing, as a contrast, a similar-capacity battery storage system (if enough battery cells were available) would -

1. Cost how much?2. Consume how much surface area or volume?3. Recurring cost, both maintenance and capital replacement?

Extrapolating from the recent Tesla mega battery thing installed in Australia:Dinorwig total capacity 9.1 GWhTesla Australian mega battery total capacity 129 MWhso it would take around 70 mega battery installations to get to the same capacity as Dinorwig.Tesla said they'd deliver the mega battery on time or do it for free - I read that they stood to loose $50,000,000 if they had to give it away, so cost could be $3,500,000,000.Area is trickier, and I guess the installation could be multi-storey to keep that under control.Recurring cost/maintenance I have no idea about either - anyone else have any idea?